<template>
    请输入姓名:<input type="text" v-model="username">
    <div>姓名是：{{ username }}</div>
    <input type="text" v-model.number="n1">+
    <input type="text" v-model.number="n2">={{ n1 + n2 }}
    </input>
</template>

<script setup>
import { ref } from 'vue'
const username = ref('zhangsan')
const n1 = ref(1)
const n2 = ref(2)
</script>